1. Field of the Invention
The present invention relates to apparatuses useful for filtering chemical gases from a fluid. More particularly, the present invention relates to adsorptive filter apparatuses for adsorbing chemical gases, especially gases causing odors, from air.
2. Description of the Related Art
Many types of devices which are adapted to remove relatively large substances such as solid or liquid particles from a fluid are known in the prior art. For example, U.S. Pat. No. 4,743,280 discloses an air filter apparatus which is formed with two V-shaped rectangular mesh filters held in place side by side within a housing and provided at an intake opening of a ventilation hood or air duct. The V-shaped filters catch grease and moisture which is in the air, and the grease and moisture drain from the vertice of the V-shape into a removable pan.
U.S. Pat. No. 4,272,262 discloses a filtering device for removing particulate matter from a gas stream, which includes a housing, and planar panel filters arranged in V-shaped banks inside the housing to clean the gas stream. U.S. Pat. No. 4,225,328 discloses an exchangeable filter element for use in nuclear installations to purify airstreams or gas streams which contain toxic or radioactive dust. The filter element includes a number of V-shaped filter pockets which are formed by filter layers made of filter paper. U.S. Pat. No. 4,359,330 discloses an air cleaning apparatus for removing dust from a flow of air which includes a housing wherein a plurality of filter assemblies are held in the flow of air by a clamping frame, and wherein inertial precleaner devices may be held for inertially separating heavy particulate matter from the air prior to filtration.
U.S. Pat. No. 4,080,185 discloses a composite filter set for placement across a gas flow path in an air conditioning duct, which includes a head frame and a number of filter pockets permanently joined to the head frame to clean dust from the gas. Finally, U.S. Pat. No. 4,865,636 discloses a pleated paper filter element which is used to filter the air intake on a diesel locomotive and which includes a plurality of pleated paper filter panels secured in a frame by V-shaped wedges such that they form plural wedge shaped air inlet and outlet spaces.
All of the above devices have the disadvantage, however, that they are adapted for the removal of relatively large substances, such as solid or liquid particles, from a fluid. Filter devices designed for this type of particle removal are generally very poor at removing chemical gases and odors from a fluid, since the size of the chemical molecules which need to be removed for gas and odor removal are so small that they easily pass through such filter devices.
Other devices are known in the prior art which are adapted to remove smaller molecules from a fluid stream. For example, U.S. Pat. No. 4,306,892 discloses a disposable tapered packet which includes an air freshening medium enclosed within the packet between two perforated walls, wherein the air freshening medium entraps odors from the air. The packet is held in the path of an air flow by a pair of lock tabs on an outer face. Also, U.S. Pat. No. 4,049,406 discloses a fluid filter housing and assembly for use in the adsorption of radioactive iodine in a fluid flow stream in a nuclear reactor installation. The filter assembly includes one or more filter elements which are foraminous containers made from a screen material which enclose carbon granules to adsorb the radioactive iodine.
However, such devices generally necessarily make use of filter material which is denser than filter material in other filter devices and which often needs to be used in a thicker layer than other filter materials. This arrangement results in a substantial pressure drop across such a filter device and a corresponding reduced fluid velocity through the filter device. Accordingly, smaller molecule filter devices need to be particularly concerned with minimizing the pressure drop thereacross, and the above-described prior art devices have the disadvantage that they fail to address such a concern.